chore: add high level classes

Signed-off-by: The one with the braid <the-one@with-the-braid.cf>

lib/src/models/location.dart

@@ -0,0 +1,30 @@
+/// Information about a location.
+class Location {
+  /// Latitude, in degrees, of the location.
+  final double latitude;
+
+  /// Longitude, in degrees, of the location.
+  final double longitude;
+
+  /// Altitude, in meters, of the location.
+  final double? altitude;
+
+  /// Text displayed on the lock screen when the pass is currently relevant.
+  /// For example, a description of the nearby location such as
+  /// “Store nearby on 1st and Main.”
+  final String? relevantText;
+
+  const Location({
+    required this.latitude,
+    required this.longitude,
+    this.altitude,
+    this.relevantText,
+  });
+
+  factory Location.fromJson(Map<String, Object?> json) => Location(
+        latitude: json['latitude'] as double,
+        longitude: json['longitude'] as double,
+        altitude: json['altitude'] as double?,
+        relevantText: json['relevantText'] as String?,
+      );
+}